The Herpetological Journal

pp.109-115

Authors: Toshiaki Hirai And Masafumi Matsui

Abstract: Rana nigromaculata and R. rugosa consumed different food resources when they coexisted in Japanese rice fields. Rana nigromaculata consumed prey from many taxa including a small proportion of ants (16% in number of the total prey items), while R. rugosa ate mainly ants (56%). However, presence of the same terrestrial prey types in the bulk of their diets suggests that the frogs forage on the ground syntopically, and do not partition their feeding sites. Moreover, the comparatively wider mouth of R. rugosa (relative to similiar sized R. nigromaculata), suggests that R. rugosa does not eat more ants because of morphological constraints. This dissimilar pattern of food resource utilization seems to have resulted from selection of different prey, as indicated by the stronger avoidance of ants by R. nigromaculata compared to R. rugosa. This food partitioning may be facilitating their coexistence in rice fields.

Keywords: Rana nigromaculata, R. rugosa, food partitioning, prey selection, syntopic foraging